Is this legal?

I was browsing and found some aluminum screws and nuts. While it may seem like a minor weight change to a robot to use all aluminum screws instead of the traditional vex steel ones, would it be legal to use these screws?

My unofficial answer is yes, these would be legal so long as they are of the same size as allowed by the rules. The material makes no difference. You can use plastic screws, too. But be aware that most aluminum screws will strip their threads more easily than the stainless steel you are probably used to. Plastic, too, is allowed but they are not as strong. My personal feeling is that they are probably not worth it.

Aluminum nuts are great and a decent weight savings. I caution against screws as they strip extremely easily. I have used them but only where I was 100% sure I would never need to remove them.

Yes, they are all VEX Robotics Competition Legal. Here is the relevant rule:

I would have to agree that plastic screws are not the best, however aluminum screws are quite strong and still 1/3 the weight of steel. Because aluminum hex drive screws can strip easily, these one have a slotted drive, which might be a bit trickier to reach in a few spots but cannot strip as long as the screwdriver is fully inserted.

I switched most of the screws on half of a lift to aluminum and measured a weight reduction of just over 100g, which might not seem like much, but over the entire robot it will really add up. I’d estimate that about 80-90% of the screws on an average robot can be aluminum without any strength issue, and high stress points should still be steel…